Convector for gas heaters



Aug; 19, 1952 A. STRAUB CONVECTOR FOR GAS HEATERS Filed Oct. 14, 1948 INVENTOR.. Auaus'rusA. 57754019 p ATTORNEYS Patented Aug. 19, 1952 CONVECTOR r011 GAsHEA'r Rs Augustus A. Straub, Cleveland; Ohio, 'assignorj to A. A. S-traub Company, Inc., a corporation of Ohio Application October 14, 1948, Serial No. 54,543

The present invention relates generally to con vection' space plates and' more particularly is concerned with anovel and very economical and useful annealing'tray; I

In the batch annealing ofcoils of metal in strip, rod'or wire form, it is customary to arrange the coils in'stacks with spaces'between adjacent coils so that heated gas may flow transversely of the coils and transmit heat rather ineffectively by conduction and convection to intermediate portions of the metal stock as well as to the outer portions thereof. Space plates or trays are the conventional. spacing means for this purpose, being'sandwiched'between adjacent coils. Because of the considerable weight of the individual coils and the multiplication of this weight when the coils are stacked, these trays must, above everything else, be of strong and durable construction and capable of supporting many times their own weight. Consequently, the trays knownvprior to this'invention have all taken the form of relatively thin doughnut-shaped rings having passagways extending from edge to edge and being closed on the upper and lower sides by imperforate metal plates. Even the strongest trays of this kind, however, will warp in use and will cause adjacent layers of coils engaged therewith to bear against each other with suflicient pressure 'to produce a weld, a very undesirable result. It is accordingly a primary object of the presentinvention' to provide atray of novel design and construction which will assure much improved results in stack annealing by enabling the direct heating of the intermediate portions as well as the outer portions of coils by means of convection currents, and will be lighter but stronger thanthe trays heretofore known.

A further object of this invention is to provide an annealing tray which may take several difierent forms based on a common, novel pattern, to meet various requirements and purposes.

It is still another object of this invention to provide an annealing tray which may be reused many times, compared to previously known trays, underrigorous conditions without warping and causing portions of coils carried thereby to 'Weld together in annealing, and without requiring maintenance or repair attentions.

An additional object of this invention is to provide an annealing tray which can be made of a minimum number of parts-of relatively simple form;;theassembly,of which can becarried out easily and quickly without requiring special highly skilled labor.

.--.A stilliurtheriobjectofrmy.inventionis to pro-f s Claima (01. 263-547 vide an annealing tray of, such form and design that the rate of gas flow through the tray canbe fixed at any desired level in. the operating range. by varying the'height or thickness of the tray, as

' by stacking trays atop of each other.

Further objects and important'advantages of the present invention will become apparent to those. skilled in the art upon consideration ofthe following detailed description thereof, reference being had to the drawings accompanying. and forming apart of the specification, in which Figure'l is an elevational view partly in section ofan annealing assembly, including trays em bodying the present invention in several'difierent forms; 1

Figure 2 is a fragmentary plan View of a tray of one form of this invention;

Figure 3 is a fragmentary plan view of another form of tray-of this invention;

Figure 4 is a fragmentary horizontal sectional view of still another form of tray of this invention having a single connecting ring; and.

Figure 5 is a fragmentary horizontal sectional view of a tray similar to that of Fig. .4, but having two rings. 7 a

As illustrated in these drawings, a tray of this invention 7 is open transversely and; generally speaking, comprises a plurality of spacedfapart curved ribs and a ring engaging said ribs and holding them together. Preferably these ribs are relatively thin and flat, disposed oneedge and curved longitudinally in the form of Archimedean curves. Also, these trays desirably have two rings concentrically related and engaging the inner and outer edge portions of the ribs, the .in-.: ner rings refiningaxial openings in the trays. The ribs may, however, be of substantiallysquare transverse cross section andimay describe circle involutes or even corrugations (Fig. 3); andthe' rings may be located intermediately of the ribs, suitably extending through openings in saidribs.

The assembly shown in Fig. 1 includes a stack of coils C of strip stock with ring-like'annealing. trays T sandwiched between adjacent coils, C, and a cup-shaped protective shell 48 enclosing the stack in a minimum space within a furnace. -'A; centrifugal fan F or equivalent blower meansis disposed below. and coaxially with the stack to. produce circulation ofheated ga;.suitably. air,; upwardly along the inner surface ofshell S and into trays T, through coils C and downwardly through the open axial section of the; stack, a1 las indicated by the several current-definingarrows. A cap piece P of ring shape is;provided. having an axial opening of reduced diameter promote air flow over the top of the stack for uniform heating and annealing results. Lip ill of the shell bears upon a supporting surface, i. e. the floor of the furnace, and is closed against penetration of furnace gas into the shell by means of a sand seal H or a liquid seal, an annular dam I2 being formed in the said surface and surrounding' lli'p l0.1'.I-Ieat'transference between the atmospheres-ofthe furnace and shell S therefore is effected through the medium of the shell walls. Means for driving the fan or blower device does not constitute a part of this invention'andwill'not be described as it may take any desired conventional form, as those skilled-'intheart will under-v stand.

The lowermost tray T, which is disposed between fan F and the first coil, :and supported on ring-like fan housing [5, generally resembles the trays illustrated in Fig. 2, having concentric inner and outer rings l'IfQand I-8 and curved ribs I94welded at their ends tov the rings. In this case. theribs and :rings'are of the sameiwidth and-approximately the same thickness. The diameterof. the outer ring, however, is sufficiently greater than .the outside. diameter of the coil above it. that an annular opening 2! is defined be'tweenthe' two for the purposes described above. Likewise, the. inner ring-is of sufliciently small diameterthat an annular opening-22 is defined between the inner surface of the coil and said innerringr .The tray in-the'second position above the fan resembles the one just. described but for the factthat its inner and outer rings "25 and 26,

respectively, are substantially narrower than ribs-21 joining them and are of a diameter more closely approaching the outside and inside diameters of the coil between these two 'trays. Ring 25 defines with the coils above and below thetray a pair, of annular openings-28. and ring 26 definesja similar pair of, openings 29--with the adjacent,- opposed, outer edges of coils C.

. The traynext above diifers from the onejust described in that the inner and outer rings 3| and 32, respectively, are of slightly larger and smaller diameters, respectively, than rings 25 and 26 .-Furthermore, ribs 33 joining rings -3I and 32, are recessed at their inner and outer edges and the'rings are disposed within these edges, being securedsuitably by means of welds.

lThe uppermost-tray differs from all those described above quite materially'in-that it has two inner and two outer rings 40 and 4 I respectively, and these-are disposedon the upperand lower surfaces,:ra-ther than-around the edges of, ribs 42,r-which" are of substantially square crosssection. a result, this tray is open-at the ends ot-the ribs and rings '40 and -4I serve thedual purposes of holdingthe ribs in relative position and-retaining the coils. Unlike the secondmand third trays, this top .tray shouldhave an internal diameter substantially less than the coils in which itis to, beused and an outsidediameter substantiallygreaterthan that vor'those said coils,-in-order to allow suflicient spaceforthe rings.

The tray :of 2 comprises an inner. ring 50, an outerring 5| concentric therewith and a plurality I of substantiallyequally spaced, relatively thin onedge ribs 52 which are secured at. their ends-to'the rings as by means'of welds. These ribs define circle involutes v and consequently the radial passageways defined by the ribs arewiderattheouterflends than at theirinner ends;- although "the" ribsare equally-spaced. It isseen .maximum free space through the tray, but, unlike ribs 52, are of corrugated form. Rings 'and'56 may'take the form of rings [-8, 26 or 4|,

shown in Fig. 1. rRings of the type of elements '32. may alsobe used, providing the inner and outer edges of ribs 51 are appropriately recessed. The tray of'Fig. 4 comprises a ring and a plurality of relatively thin, on-edge and substantially equally spaced ribs 6| defining circle involutes and having transverse openings register to receive ring 60- which .secures and maintains the ribs together. .In this casethe. ribs are necessarily somewhat wider .than .-the .ring, which preferably takes the-form of arod. Each of ribs-6| is-provided with four spacing lugs .52 so that .when the ribs are assembled together the lugs .upon adjacent ribs will engage. each other and .serve to maintain. the .ribsin .predetermined spaced relation during .use.

The tray of Fig. 5 closely resembles thetray just described, having a pluralityv ofsubstantially equally spaced relatively .thin, .on-edgecurved ribs 68 provided with spacingflugsi69. .near..their inner and outerv edges, .and'havingiransverse openings to receive connecting .means. This means, however, difiers'from thatofl the previous tray, .comprising .two concentric rings I10 .substantially equally. spaced apart. from .theen'ds .of ribs 68.and .eachother, as.illustrated. .Substantial. additional stabilityis thereby realizedat the cost of a negligible amount of free space, rings 10 being ofsub'stantiallythestmecross-sectional shape and dimensionsas ringBO.

Although 11 have v described. the. present. invention in several preferred forms, I donut-wish.- to be limited to. thesetfor-ms. as.-will-;-be..clear from the appended. claims. .It will be understood,--:for instance, that the ribs need. not-be of Archimedean curve form,- -but-may describe-circle-involutes, circumferential tangents and .the like, or may be of corrugated form, so longas.-.-they give substantially the advantages. and results :stated above. Also, the bar widthmay be variedifrom the proportionsxshown .to/meet various requirementsand I demands arising with:difierentg gas volumes and speeds and-.-difierenttypessofwannealing equipment.

--Having :thusdescribed the; presentr invention so thatthose skilled ine-the art amay'be-ab'le-i-to understandand. practice the same, Iw state that what I desire .to securewby LettersrPatent :Ilefined'in what is claimed.

What is claimed. is:

l. A. generally: ring-shaped. annealing ttrayato be disposed between and tocngage rtwo stacked coils :ofametal. stock- :to. be heated and. annealed comprising a pluralityrofcsubstantially:uniformly spaced, .1-longitudinallyecurved, metal :-';r'ibs.:;cooperating. to :define a plurality aofztopeneended channels: through which" heating fluid may tsflow, and means includingia metal ring -engaging'eand securing said ribs togetherpsaidtimetal ribs having spaced inner and outerends andfhaving edge portionsiiexposed itorithe aeritire flengthiiofithe ribs and cooperating with each other to define a side of the tray for engagement with a coil to be annealed, and said ring being spaced from the coil-engaging side of the tray between the inner and the outer extremities of the ribs.

2. A generally ring-shaped annealing tray to be disposed between and to engage two stacked coils of metal stock to be heated and annealed comprising a plurality of substantially uniformly spaced, longitudinally-curved, metal ribs cooperating to define a plurality of open-ended channels through which heating fiuid may fiow, and means including metal concentric rings circumferentially securing said ribs together at their inner and outer extremities, said rings each being of thickness substantially less than one-half the thickness of the tray, and said metal ribs having spaced inner and outer ends defining inner and outer peripheries of the tray and having edge portions exposed for substantially the entire length of the ribs and cooperating with each other to define one side of the tray for engagement with a coil to be annealed.

3. A generally ring-shaped annealing tray to be disposed between and to engage two stacked coils of metal stock to be heated and annealed comprising a plurality of substantially uniformly spaced, longitudinally-curved, metal ribs cooperating to define a plurality of open-ended channels through which heating fiuid may flow, and means including concentric metal rings circumferentially engaging and securing said ribs together at their inner and outer extremities, said metal ribs having spaced inner and outer ends and having edge portions exposed for the entire length of the ribs and cooperating with each other to define top and bottom sides of the tray for engagement with coils to be annealed.

4. A generally ring-shaped annealing tray to be disposed between and to engage two stacked coils of metal stock to be heated and annealed comprising a plurality of substantially uniformly spaced, longitudinally-curved, metal ribs cooperating to define a plurality of open-ended channels through which heating fiuid may fiow, and means including a pair of metal rings engaging and securing said ribs together at their outer extremities and another pair of metal rings concentric with the first ring pair and engaging and securing said rings together at their inner extremities, said metal ribs having spaced inner and outer ends and having edge portions exposed for the entire length of the ribs and cooperating with each other to define top and bottom sides of the tray for engagement with coils to be annealed, and said rings being disposed on said top and bottom sides of the tray.

5. A generally ring-shaped annealing tray to be disposed between and to engage two stacked coils of metal stock to be heated and annealed comprising a plurality of substantially uniformly spaced, longitudinally-curved, metal ribs cooperating to define a plurality of open-ended channels through which heating fiuid may flow, and means including concentric metal rings circumferentially securing said ribs together, said metal ribs having spaced inner and outer ends and having edge portions exposed for the entire length of the ribs and cooperating with each other to define top and bottom sides of the tray for engagement with coils to be annealed, and said rings being of thickness substantially less than one-half the thickness of the tray and engaging the inner and outer extremities of the ribs between said top and bottom sides of the tray.

6. A generally ring-shaped annealing tray to be disposed between and to engage two stacked coils of metal stock to be heated and annealed comprising a plurality of substantially uniformly spaced, longitudinally-curved, metal ribs cooperating to define a plurality of open-ended channels through which heating fluid may flow, and. means including concentric metal rings circumferentially securing said ribs together, said metal ribs having spaced inner and outer ends and having edge portions exposed for the entire length of the ribs and cooperating with each other to define top and bottom sides of the tray for engagement with coils to be annealed, and said rings being of thickness substantially the same as the thickness of the tray and engaging the inner and the outer extremities of the ribs.

AUGUSTUS A. S'I'RAUB.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,896,286 Burns et al Feb. 7, 1933 2,081,990 Eberwein June 1, 1937 2,334,439 Pierce Nov. 16, 1943 2,362,823 Hubbell Nov. 14, 1944 2,414,130 Wilson Jan. 14, 1947 2,489,012 Dailey, Jr. Nov. 22, 1949 FOREIGN PATENTS Number Country Date 588,052 France Apr. 29, 1925 OTHER REFERENCES Pages 1486 and 1487 of September 1946 issue of Industrial Heating No. 9, vol. XIII, National Industrial Publishing (30., Pittsburgh, Pa. 

